1. Technical Field
This invention relates to a sound reproduction system to produce sound synthesis from an array of exciters having a multi-channel input.
2. Related Art
Many sound reproduction systems use wave theory to reproduce sound. Wave theory includes the physical and perceptual laws of sound field generation and theories of human perception. Some sound reproduction systems that incorporate wave theory use a concept known as wave field synthesis. In this concept, wave theory is used to replace individual loudspeakers with loudspeaker arrays. The loudspeaker arrays are able to generate wave fronts that may appear to emanate from real or notional (virtual) sources. The wave fronts generate a representation of the original wave field in substantially the entire listening space, not merely at one or a few positions.
Wave field synthesis generally requires a large number of loudspeakers positioned around the listening area. Conventional loudspeakers typically are not used. Conventional loudspeakers usually include a driver, having an electromagnetic transducer and a cone, mounted in an enclosure. The enclosures may be stacked one on top of another in rows to obtain loudspeaker arrays. However, cone-driven loudspeakers are not practical because of the large number of transducers typically needed to perform wave field synthesis. A panel loudspeaker that can accommodate multiple transducers is usually used with wave field synthesis. A panel loudspeaker may be constructed of a plane of a light and stiff material in which bending waves are excited by electromagnetic exciters attached to the plane and fed with audio signals. Several of such constructed planes may be arranged partly or fully around the listening area.
While only the panel loudspeakers generate sound, wave theory also may be used so that the listener may perceive a synthesized sound field, or virtual sound field, from virtual sound sources. Apparent angles, distances and radiation characteristics of the sources may be specified, as well as properties of the synthesized acoustic environment. The exciters of the panel loudspeakers have non-uniform directivity characteristics and phase distortion, windowing effects due to the finite size of the panel. Room reflections also introduce difficulties of controlling the output of the loudspeakers.